1. Field of the Invention
The invention relates to an oil pan inner tank valve structure that is able to close a valve port, formed at the bottom wall of an inner tank of a double-tank oil pan, with a float valve arranged below the valve port.
2. Description of Related Art
As a float valve provided for an existing oil pan inner tank valve structure of this type, there is known a structure that a valve element arranged below a valve port and a floating element arranged above the valve port are coupled to each other by a valve shaft that extends through the valve port (for example, see Japanese Patent No. 4420026 (from line 43 in the paragraph 18 to line 9 in the paragraph 19, FIG. 5)). The float valve is configured so that the floating element moves upward or downward in accordance with an oil surface in the inner tank to cause the valve element to open or close the valve port.
Incidentally, in the above described existing oil pan inner tank valve structure, there is a problem that the floating element, the valve shaft and the valve element are arranged in the vertical direction and, therefore, the size of the structure increases. In addition, there is another problem that the float valve is inclined because of flow of oil in the inner tank during operation of an engine, inclination of an oil surface during running on a ramp, or the like, and then the valve shaft is caught inside the valve port to cause abnormal valve opening.